Google's Cars Sniff Out Natural Gas Leaks to Deliver Cleaner Air

Of all the things to be leaking methane on Staten Island in New York City—corroded gas pipes, sewers, the Fresh Kills dump—who would have suspected the mail truck? But as I circled a Staten Island neighborhood in a specially equipped Google car, it was a parked mail truck that proved to be sending the biggest leak of methane skyward.

This specially outfitted Subaru has methane detection equipment threaded through its front grill and connected to a spectrometry machine in the trunk for near real-time analysis of incoming air samples. Other than that, it's just another one of an undisclosed number of cars used by Google to take photos along streets that can be seen on its maps in Street View mode. I was tagging along with a driver who was using it as a demonstration of the new methane-detecting partnership between Google and the Environmental Defense Fund. Methane is a potent greenhouse gas, which over decades, traps at least eight times more heat than carbon dioxide, driving global warming even faster.

Steve Hamburg, a forest ecologist turned chief scientist at the environmental group, found such natural gas vehicles to be the biggest surprise of the test runs of this partnership. Clearly, vehicles that run on natural gas can mess up the detection of leaks from underground. During the test drives "we saw a level going down the street day after day," Hamburg recalled, before we headed out on our methane-detecting expedition to New York City's fifth borough on a muggy summer day. "That was a bus," he added, a bus that runs on natural gas and leaks some of it, like the New York City "Clean-Air" buses powered by compressed natural gas.

But New York City also has abundant methane leaks from old pipelines, as proved by the test runs during this pilot phase in Staten Island. The point of this partnership between Google Earth Outreach and EDF is to test whether a better map of methane leaks could be acquired by the Street View fleet, recognizable by the unmistakeable Google Maps paint job and towering pan-optic camera affixed to the roof making the car 7.1 meters tall. The idea is to add another tool for utilities to use in determining what repairs to undertake first, given limited budgets, by delivering an estimate of exactly how much gas is escaping from a given leak.

The test runs to date involved three Street View cars driving methane routes in three locations: Boston, Indianapolis and Staten Island. The results of those drives—roughly 15 million individual readings—have been released in the form of maps that show thousands of leaks. Boston and Staten Island both averaged one leak for every mile driven, thanks to older infrastructure. On the other hand, the Street View car drove roughly 200 miles for every leak detected in Indianapolis, where pipe upgrades have paid off. Even better, Indianapolis had no major leaks; Boston and Staten Island both had several red dots on their maps, indicating places where methane was leaking at a rate of more than 60,000 liters per day.

Although such relatively small methane emissions are not an immediate safety concern, they do have an outsized impact on climate change. Methane is less prevalent in the atmosphere than CO2, but traps more heat over its relatively short time of a few decades in the atmosphere before it breaks down into yet more CO2 that then traps yet more heat over its time in the atmosphere that can stretch for centuries or millennia. "We want to minimize losses," Hamburg said. "We're losing product, increasing climate change, and increasing air pollution."

Historically, data like this was only known to utilities, or when it became significant enough to pose a safety danger and could be detected by sensitive equipment such as the human nose. "This is the democratization of environmental data," Hamburg added. The data is not exactly surprising in its entirety. Indianapolis, which replaced its natural gas pipelines over the last several decades, has few leaks compared with a city like Boston with older infrastructure. More than 40 percent of Boston's natural gas pipes are cast iron or uncoated steel pipes that corrode more easily, and more than half the pipes are 50 years old or more.

Leaks are most common in areas that predate the widespread use of natural gas. For example, my neighborhood in Brooklyn—Gowanus—has become a Superfund site thanks in part to facilities there in the 19th century that turned coal into so-called town gas. The town gas was used to fuel gas-fired lamps, but then that infrastructure was, in some cases, taken over to deliver natural gas to homes. "These pipes were put in the ground for a different type of gas, a different moisture content," Hamburg explained. "It's not surprising they need to be replaced by modern plastic pipes."

Staten Island was chosen because of the challenge of detecting leaks in the presence of other sources of methane, like the Fresh Kills landfill, where feasting microbes turn decomposing garbage into methane. The normal atmosphere of Brooklyn and Staten Island seemed to hover around 2 parts-per-million of the methane molecule in the atmosphere, except when crossing the Verrazano Bridge over New York harbor, where readings drop even lower. Driving down the highway that cuts through Fresh Kills, methane readings spiked as high as 4.6 ppm, because of the methane seeping out from within the landfill. Yet driving the perimeter of the methane recovery plant on the outskirts of those sprawling midden mounds, readings never went above that background level of around 2 ppm. "I'm impressed," Hamburg said.

Landfills, sewers and even cattle, when the wind is right, can cause spikes that can obscure leaks. Such spikes usually registered around 10 ppm but drivers saw spikes as high as 30 or even 50 ppm. To compensate for such other sources—including more and more ubiquitous natural gas-fueled vehicles thanks to the glut of cheap gas—the maps err on the side of being conservative. "When in doubt, don't put it down," Hamburg said. "We'd rather have a false negative than a false positive" so that there is no unnecessary expense in undertaking repairs. And many of these findings from drives in 2013 are likely already out of date as utilities constantly repair and maintain their natural gas infrastructure.

Driving slowly through city streets and neighborhoods, the Google Street View car is always an object of curiosity. On our test run, people stopped to gawk, snapped photos or waved. We traveled just about as slowly as the car from a local driving school, presumably without a professional driver behind the wheel. Though the cameras were turned off during this proof-of-concept phase, the idea is to one day use the Street View fleet—Google declined to specify how many cars are in that fleet or allow their driver to be quoted—to map city streets and methane emissions at the same time. "This is the first time using Street View cars for an environmental project," said Karin Tuxen-Bettman, program manager for Google Earth Outreach who helped lead this partnership. "Environmental air quality affects everyone and we like those big problems, to see how Google can play a part in solving those."

The same equipment can also be used to tackle other forms of air pollution, including the soot responsible for asthma and other lung ailments. "Methane is just the first one," Tuxen-Bettman said, a point reaffirmed by EDF's Hamburg.

This inaugural effort is part of EDF's campaign, launched in 2012, to better understand the benefits and dangers of natural gas. It involves 90 institutions and corporations as well as more than 100 scientists, and includes research such as the best ways to measure concentrations in the atmosphere as well as detect leaks in natural gas infrastructure, from the original well drilled to the final user. The preliminary research suggests that methane leaks could be cut at an additional cost of roughly one cent per thousand cubic feet of natural gas produced and moved.

On my drive, the mail truck parked by the side of a suburban road in Staten Island delivers the largest spike I see—4.7 ppm, just surpassing New York City's largest landfill from the highway. That spike disappears when the mail truck moves on. "That's why it's so important to drive roads at least twice," Hamburg noted. "So even do a third pass to see if it's infrastructure or a vehicle."

The trick now is to drive all that road, sniffing out the worst leaks at a clip of 130 to 240 kilometers per day, mostly in circles. Thousands of kilometers of cast iron pipes are underneath the roads of New Jersey alone, just across the water from here. And all those roads are just waiting for someone to drive them, sniffing out leaking methane, delivering cleaner air and combating climate change. Or as Hamburg asked me: "When was the last time you did a joy ride in New York City?"

The views expressed are those of the author and are not necessarily those of Scientific American.

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